[code]
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity"
android:background="#0470d9"
android:orientation="vertical" >
<Button
android:id="@+id/opbutton"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#ddd"
android:gravity="center"
android:layout_gravity="center"
android:text="Open" />
<Button
android:id="@+id/clbutton"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#ddd"
android:layout_marginTop="10dp"
android:text="TurnOff" />
<Button
android:id="@+id/btnexit"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#ddd"
android:layout_marginTop="200dp"
android:text="Exit" />
</LinearLayout>
[/code]